1. Field of the Invention
The invention relates to a tactile braille or graphic display with a laminar display carrier with pattern points which are raised in their tangible positions and are formed by the hemispherical surfaces of feeler balls projecting through openings in the top of the display carrier, which balls are selectively brought into the tangible position by adjusting associated locking elements.
2. Description of the Prior Art
Braille's type for the blind is composed of letters or characters which consist of combinations of either six or eight tangible pattern points disposed under or next to one another, and the pattern is also characterized by varied spacing of the pattern points. These combinations are usually described as "shapes". A braille pattern spacing of approximately 3 mm is suitable for braille type output devices with feeler buttons.
Electromagnetic output devices for braille type are known which are provided with a panel which exhibits a pattern of holes with the basic structure of the braille characters. These holes accomodate pins which can be moved upwards individually by means of electromagnets such that the externally projecting pins as a whole represent the braille characters. In one of these known embodiments the externally projecting ends of the pins are hemispherical. All these known embodiments of reading devices serve for presentation of a text in chunks determined by the size of the display field. When a fairly lengthy text is to be displayed in a tangible form with the aid of such devices, this text must be broken up into sections according to the size of the recording field and stored and this stored data is then converted into electrical signals.
U.S. Pat. No. 3,987,438 describes a braille type output device in which each feeler button has two magnets which are disposed one under the other in the axial direction at least and at least one of which takes the form of an electromagnet. When energized electrically the magnets produce a force in the axial direction of the feeler button. This force lifts or lowers the feeler button by means of a magnetic coil depending on the direction of energization. Each feeler button is provided with a mechanical magnetically controllable locking device which only acts on the feeler button. Here the drawback is the large number of mechanical components required to produce a plurality of buttons when this is used for a graphic display.
German OS No. 26 08 659 also describes a braille type output device in which the feeler pins in the form of permanent magnets are provided to represent the tangible points, which feeler pins are displaceable by means of one or two associated, also permanently magnetic carrier pins. The feeler and carrier pins are arranged in rows with unlike poles adjacent one another and the feeler pins are displaced in their longitudinal direction by magnetically tripped tilting movements of the carrier pins. During the constant alternating magnetic action on the carrier pins there is a risk of demagnetization and thus impairment of correct operation.